1. Field of the Invention
The present invention relates to a method of storing and retrieving image data. More specifically, the invention relates to a method of storing secondary data, such as memos added to a document image as index data relating to the document image, and to a method of retrieving a document image by utilizing the secondary data.
2. Description of the Prior Art
Accompanying the recent trend toward putting into practice an optical disc device which is capable of storing large amounts of data, attention has been given to a document image filing system as a new document control means to electronically file document data and to retrieve the data by using a display device. If the content of a document is treated as an image, the document which includes figures and photographs in addition to characters can be electronically filed. Therefore, a wide range of documents, such as general literature, books and slips, design drawings, written contracts, and the like can be stored in a memory device.
According to a conventional retrieval system, index data, such as names of the documents, classification codes, keywords and the like are registered through a keyboard to identify the document images. To retrieve the data, a user designates the index data so that the contents of the corresponding document are produced on the display device. A system of this type has been disclosed, for example, in a journal "Nikkei Computer" published by Nikkei McGraw-Hill Co., Dec. 26, 1985, pp. 62-64. Since items common to each of the documents have been selected, the above-mentioned retrieval data is not helpful to directly retrieve a document that is being sought if the user does not remember the name of the literature or the keyword or if he remembers them vaguely. In this case, the document images are displayed successively to retrieve the correct one by visual inspection.
As a method to facilitate the retrieval of the document image, the applicant of the present invention has proposed a method of retrieving an image in Japanese Patent Application No. 55073/1983 (Japanese Patent Laid-Open No. 183458/1984, U.S. Ser. No. 594690) according to which secondary reference data, such as memos specific to the image data are registered, and the image data is specified with reference to the thus registered data at the time of retrieval.